JP2005276856A - Area sensor and image scanner using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an area sensor and an image scanner capable of dealing with the entire region of given optical density with a simplified constitution. <P>SOLUTION: The area CCD sensor 20 used for a film scanner 10 includes photoelectric conversion regions 22, 24, 26, 28 each having a light receiving surface divided into four subregions and arranged in the direction of an arrow A. The photoelectric conversion regions 22, 24, 26 include high density light receivers 22a, 24a, 26a having high filter transmittance, and low density light receivers 22b, 24b, 26b having low filter transmittance. Each is bordered a substantially at the central portion in the direction of the arrow A as a boundary. A saturation level of the high density light receivers 22a, 24a, 26a to a light quantity of an image provided to the photoelectric conversion regions 22, 24, 26 is different from that of the low density light receivers 22b, 24b, 26b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an area sensor and an image reading apparatus using the area sensor, and more specifically to an area sensor that converts light having different wavelengths into electric signals in a plurality of photoelectric conversion regions and an image reading apparatus using the area sensor.

  In general, an image reading apparatus that reads an image formed on an exposed medium such as a photographic film includes a CCD (Charge Coupled Device) sensor that detects (acquires) light passing through the exposed medium as data as an image sensor. It is known to be used. In a CCD sensor, photoelectric conversion elements such as photodiodes arranged on a light receiving surface accumulate light that has passed through the exposed medium as signal charges, so that an image formed on the exposed medium is data. Get as.

In recent years, along with the demand for downsizing of image reading devices and higher resolution of read images, CCD sensors have been downsized and the number of pixels has increased. For example, about 5 million chips on a 7.25 mm × 5.44 mm chip. (11.8 inch size, 5 million pixels) area CCD sensors and the like are placed on the market.
In such a CCD sensor that is becoming smaller and higher in pixel count, minute photodiodes are arranged without gaps on the light receiving surface, so that the received light amount (charge accumulation amount) of each photodiode is reduced, and the sensitivity of the CCD sensor is increased. It will decline. As a result, problems such as deterioration of the S (Signal) / N (Noise) ratio of the CCD sensor and reduction of the light density range (dynamic range) that can be obtained by the CCD sensor occur.

  In order to solve this type of problem, for example, in Patent Document 1, the light receiving surface is divided into photoelectric conversion regions corresponding to R light, G light, and B light, and the same in a plurality of pixel columns in each photoelectric conversion region. An area CCD sensor that reads out multiple images (light) and an image reading apparatus using the same are disclosed. According to the technique of Patent Document 1, it is possible to read the image formed on the medium to be exposed as image data having an excellent S / N ratio by increasing the amount of charge and thus the output signal by multiple readout. However, it is difficult to effectively expand the dynamic range of the area CCD sensor even if multiple readout is performed, and the density range of the image formed on the exposed medium and the density range of light passing through the exposed medium is therefore the area CCD. If it is wider than the dynamic range of the sensor, white and black may occur.

As a technique aiming at dealing with the entire density range of light passing through the exposure medium, for example, Patent Document 2 discloses that light passing through the exposure medium is divided and two line CCD sensors have different exposure conditions ( A technique is disclosed in which the saturation level and thus the dynamic range of each line CCD sensor with respect to light passing through an exposed medium is made different by giving the same image in terms of light quantity. In Patent Document 2, the light receiving surface is divided into photoelectric conversion regions corresponding to R light, G light, and B light, and a plurality of pixel columns in each photoelectric conversion region are different from light passing through the exposed medium. An area CCD sensor having a saturation level is also disclosed.
JP 2003-61106 A JP-A-6-233052

However, the technique of Patent Document 2 requires another member such as a half mirror for giving light to each line CCD sensor under different exposure conditions. Further, in the area CCD sensor disclosed in Patent Document 2, it is not clearly disclosed how to make the saturation level for light passing through the exposed medium different in a plurality of pixel columns in each photoelectric conversion region.
SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide an area sensor and an image reading apparatus that can cope with the entire density range of light applied with a simple configuration.

  In order to achieve the above-described object, the area sensor according to claim 1 is a light-receiving surface in which a large number of pixel rows in which a large number of photoelectric conversion elements are arrayed in a predetermined direction are arrayed in a direction orthogonal to the predetermined direction, at least red In order to acquire light, green light, and blue light as electrical signals, a plurality of photoelectric conversion regions provided by dividing a light receiving surface so as to include a plurality of pixel columns, respectively, and a plurality of photoelectric conversion regions provided respectively Area sensor including a filter that transmits light having a wavelength of red, green light, and blue light, each photoelectric conversion region corresponding to red light, green light, and blue light includes a plurality of regions having different filter transmittances. It is characterized by being divided and provided in the direction.

  An image reading apparatus according to a second aspect uses the area sensor according to the first aspect.

  In the area sensor according to claim 1, in each photoelectric conversion region corresponding to red light, green light, and blue light, a plurality of regions having different transmittances of each filter divide each photoelectric conversion region in a predetermined direction. It is provided as follows. Therefore, the saturation levels of the plurality of regions with respect to the light applied to each photoelectric conversion region are different from each other, and each photoelectric conversion region has a plurality of dynamic ranges for each of the plurality of regions. It is possible to deal with the entire density range with a simple configuration.

  In the image reading apparatus according to the second aspect, by using the area sensor according to the first aspect, an image can be acquired in a density range similar to the density range of the image formed on the exposed medium.

  According to the present invention, it is possible to cope with the entire density range of light to be provided with a simple configuration.

Hereinafter, a case where the present invention is applied to a film scanner 10 for reading an image from a photographic film F which is an example of a medium to be exposed will be described with reference to the drawings.
1 and 2, a film scanner 10 includes a light source unit 12 that gives light to a film F on which an image (frame image) is formed, a film carrier 14 that conveys the film F, and light that has passed through the film F. It includes a lens 16 that forms an image and a CCD unit 18 that converts an image of the frame image formed on the film F into an electrical signal (data).

  The light source unit 12 includes a light emitter such as an LED (Light Emitting Diode) (not shown), and gives light to the film F conveyed on the film carrier 14 (not shown in FIG. 2).

  The light emitter used in the light source device 12 is not limited to an LED, and may be a halogen lamp, a xenon lamp, or the like.

A film F on which a frame image is formed is disposed on the film carrier 14. The film carrier 14 transports the film F at a constant speed in the direction of arrow A (sub-scanning direction) by transport means such as a roller (not shown).
Below the film carrier 14, a lens 16 for forming an image of light transmitted through the film F is disposed. The light transmitted through the film F conveyed on the film carrier 14 is given to the area CCD sensor 20 of the CCD unit 18 by the lens 16 as an image (light) of a frame image.

  Note that either a single focus lens or a zoom lens may be used as the lens 16.

  The CCD unit 18 includes an area CCD sensor 20 for converting light into analog data and A / D converters 30, 32, 34, provided for the photoelectric conversion regions 22, 24, 26, and 28 of the area CCD sensor 20, respectively. 36.

  The area CCD sensor 20 is provided with photoelectric conversion regions 22, 24, 26, and 28 so that the light receiving surface is divided into four and aligned in the arrow A direction. The photoelectric conversion regions 22, 24, 26, and 28 convert red (R) light, green (G) light, blue (B) light, and infrared light (IR) into analog data, respectively, among the images of the frame image provided by the lens 16. Convert.

Specifically, referring to FIG. 3, in the photoelectric conversion regions 22, 24, 26, and 28, a large number of pixel columns 38 (shown by broken lines) are arranged in the direction of arrow A. The pixel row 38 is configured by arranging a large number of photodiodes (not shown) that are photoelectric conversion elements in the arrow B direction (main scanning direction).
For example, about 500 pixel arrays 38 are arranged per photoelectric conversion region 22, 24, 26, 28, and about 2500 photodiodes are arranged per pixel array 38. That is, about 1.25 million photodiodes are arranged in each of the photoelectric conversion regions 22, 24, 26, and 28, and the area CCD sensor 20 has a number of pixels of about 5 million pixels.

  The number of pixels of the area CCD sensor 20 is not particularly limited, and the area CCD sensor 20 having an arbitrary number of pixels can be used.

  In FIG. 3, the light receiving surface is divided so that the photoelectric conversion regions 22, 24, 26, and 28 have the same area, but the R light, G light, and B light of the image given on the area CCD sensor 20 are divided. The light receiving surface may be divided so that the ratios of the areas of the photoelectric conversion regions 22, 24, and 26 differ according to the wavelength distribution characteristics.

  Filters (on-chip filters) that transmit R light, G light, B light, and IR are provided in a large number of photodiodes constituting each pixel column 38 of the photoelectric conversion regions 22, 24, 26, and 28. A large number of photodiodes constituting each pixel column 38 of the photoelectric conversion regions 22, 24, 26, and 28 convert the R light, G light, B light, and IR, respectively, into signal charges and store them.

  Note that the filters provided in the photoelectric conversion regions 22, 24, 26, and 28 are not limited to the on-chip filters provided in the respective photodiodes, and plate-like filters are attached to the photoelectric conversion regions 22, 24, 26, and 28, respectively. You may make it attach.

  In the photoelectric conversion regions 22, 24, and 26, the high-concentration light receiving portions 22 a, 24 a, and 26 a that have high transmittance of the photodiode on-chip filter that constitutes the pixel row 38 and the photodiode on-chip filter that constitutes the pixel row 38 The low-concentration light-receiving portions 22b, 24b, and 26b having low transmittance are provided at substantially the center (indicated by a thin line) in the direction of arrow A, respectively.

  The light intensity incident on each photodiode differs between the high-density light-receiving portions 22a, 24a, and 26a and the low-density light-receiving portions 22b, 24b, and 26b with respect to the light amount of the image applied to the photoelectric conversion regions 22, 24, and 26. Accordingly, as shown in FIG. 4, the saturation levels of the high-density light-receiving portions 22a, 24a, and 26a and the low-density light-receiving portions 22b, 24b, and 26b with respect to the light amount of the image given to the photoelectric conversion regions 22, 24, and 26 Different from the saturation level, the high-density light receiving portions 22a, 24a, 26a and the low-density light receiving portions 22b, 24b, 26b have different dynamic ranges DL1, DL2. The high-concentration light-receiving portions 22a, 24a, and 26a and the low-density light-receiving portions 22b, 24b, and 26b have different dynamic ranges DL1 and DL2, respectively, so that the photoelectric conversion regions 22, 24, and 26 have the dynamic range DL.

  The photoelectric conversion regions 22, 24, and 26 have a simple configuration in which high-density light receiving portions 22a, 24a, and 26a and low-density light receiving portions 22b, 24b, and 26b having different filter transmittances are provided, so that the dynamic range is expanded. It is possible to deal with the entire density range of the R light, G light, and B light provided.

  The high concentration light receiving portions 22a, 24a, and 26a and the low concentration light receiving portions 22b, 24b, and 26b are the noise levels of the respective photodiodes, that is, the high concentration light receiving portions 22a, 24a, and 26a and the low concentration light receiving portions 22b, 24b, and 26b. In consideration of the noise level, the dynamic ranges DL1 and DL2 are provided so as not to overlap.

  Returning to FIG. 3, the high-density light receiving portions 22a, 24a, and 26a, the low-density light receiving portions 22b, 24b, and 26b, and the photoelectric conversion region 28 are each horizontally adjacent to the last pixel row 38 in the arrow A direction. A transfer register (indicated by a one-dot chain line, hereinafter referred to as HCCD) 40 is provided. Each HCCD 40 receives signal charges accumulated in each photodiode constituting each pixel column 38 of the high-density light-receiving portions 22a, 24a, and 26a, the low-density light-receiving portions 22b, 24b, and 26b, and the photoelectric conversion region 28, respectively. Signal charges are sequentially transferred from a vertical transfer register (hereinafter referred to as VCCD) that is not shown.

  The area CCD sensor 20 operates at a predetermined timing synchronized with the conveyance of the film F. The high-density light receiving portions 22a, 24a, and 26a, the low-density light receiving portions 22b, 24b, and 26b, and the pixel arrays 38 in the photoelectric conversion region 28 repeatedly scan an image that changes as the film F is conveyed in the direction of arrow B. The entire image of one frame image is converted into signal charges (photoelectric conversion). That is, the same image is photoelectrically converted and read out to the VCCD (multiple readout) in each pixel row 38 of the high-density light-receiving portions 22a, 24a, and 26a, the low-density light-receiving portions 22b, 24b, and 26b, and the photoelectric conversion region 28. It will be.

  The signal charge accumulated per scan of each pixel row 38 is read out to the VCCD and sequentially transferred to the HCCD 40. The signal charges transferred to the HCCD 40 of the high density light receiving portions 22a, 24a, 26a and the low concentration light receiving portions 22b, 24b, 26b of the photoelectric conversion regions 22, 24, 26 are respectively input to the photoelectric conversion regions 22, 24, 26. The analog data is output to the connected A / D converters 30, 32, and 34. Similarly, the signal charge transferred to the HCCD 40 in the photoelectric conversion area 28 is output as analog data to the A / D converter 36 connected to the photoelectric conversion area 28.

  As the area CCD sensor 20, either an interline transfer type or a frame transfer type charge transfer type area CCD sensor 20 may be used.

Returning to FIG. 1, the A / D converters 30, 32, 34, and 36 sequentially convert the input analog data into digital data and output the digital data to the image processing unit 42.
The image processing unit 42 holds the input digital data in the memory 42a and performs various image processing on the input digital data.

  The image processing unit 42 is converted into the same image (linear image) photoelectrically converted by the pixel rows 38 of the high-density light receiving units 22a, 24a, and 26a and the low-density light receiving units 22b, 24b, and 26b in the memory 42a. The digital data based thereon are sequentially synthesized, and a plurality of digital data obtained thereby are further synthesized so as to correspond to one frame image, and output to the control unit 44 as frame image data.

  Similarly, the image processing unit 42 sequentially synthesizes digital data based on the same image photoelectrically converted by each pixel row 38 in the photoelectric conversion region 28 in the memory 42a, and combines the plurality of digital data obtained thereby into one. Further synthesis is performed so as to correspond to the frame image, and it is output to the control unit 44 as flaw detection frame image data.

  The digital data synthesis performed in the image processing unit 42 may be performed in any way as long as the frame image data and the flaw detection frame image data can be finally obtained. For example, digital data based on a large number of images photoelectrically converted by one pixel column 38 is synthesized as digital data corresponding to one frame image, and this is performed for all the pixel columns 38 and then one frame. You may make it synthesize | combine many digital data corresponding to an image.

  The control unit 44 includes a hard disk drive (HDD: including a hard disk) (not shown) that stores various programs, control data, and the like, and records frame image data input from the image processing unit 42 in the HDD. The frame image data recorded in the HDD of the control unit 44 is input to, for example, a printing apparatus (not shown), and an image based on the frame image data is printed on photographic paper or the like.

  In addition, a display unit 46 such as a CRT is connected to the control unit 44, and frame image data and flaw detection frame image data input from the image processing unit 42 to the control unit 44 are displayed via the control unit 44. Is displayed.

  In general, the film scanner 10 performs pre-scanning (pre-reading), and after determining the quality of an image obtained by the pre-scanning, the main scanning (main image reading) is performed. The flaw detection frame image data is displayed on the display unit 46 when pre-scanning is performed. When performing the main scan, the photoelectric conversion area 28 of the area CCD sensor 20 may not be operated.

  Further, an input unit 48 such as a keyboard and a mouse is connected to the control unit 44, and various settings and data input are performed from the input unit 48. The control unit 44 controls the operation of the film scanner 10 based on information input from the input unit 48 and information input from each component of the film scanner 10. Specifically, in this embodiment, the transport speed of the film F by the film scanner 14, the operation timing of the area CCD sensor 20, the image composition processing operation of the image processing unit 42, and the like are controlled by the control unit 44.

  According to such a film scanner 10, the area CCD sensor 20 having a wide dynamic range with respect to the R light, G light, and B light given so as to correspond to the entire density range of the frame image of the film F is used. Frame image data having a density range similar to the image density range can be acquired.

  In the above-described embodiment, the case where the high-concentration light-receiving portions 22a, 24a, and 26a and the low-density light-receiving portions 22b, 24b, and 26b are provided in the photoelectric conversion regions 22, 24, and 26 has been described. , 24, 26 may be divided into three or more regions.

  In the above-described embodiment, the case where the area CCD sensor 20 is applied to the film scanner 10 has been described. However, the area CCD sensor 20 may be applied to, for example, a digital camera or a digital video camera.

It is a block diagram which shows the film scanner to which the area CCD sensor of one Embodiment of this invention is applied. It is a perspective view which shows the positional relationship of the light source part of the film scanner of FIG. 1, a film, a lens, and an area CCD sensor. It is a top view of an area CCD sensor. It is an illustration figure which shows the dynamic range of a high concentration light-receiving part and a low concentration light-receiving part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film scanner 12 Light source part 14 Film carrier 16 Lens 18 CCD unit 20 Area CCD sensor 22, 24, 26, 28 Photoelectric conversion area 22a, 24a, 26a High density light-receiving part 22b, 24b, 26b Low density light-receiving part

Claims (2)

A light-receiving surface in which a large number of pixel arrays in which a plurality of photoelectric conversion elements are arranged in a predetermined direction are arranged in a direction perpendicular to the predetermined direction;
A plurality of photoelectric conversion regions provided by dividing the light receiving surface so as to include a plurality of pixel columns in order to obtain at least red light, green light, and blue light as electric signals; and the plurality of photoelectric conversion regions Each of the area sensors includes a filter that is provided and transmits light of a predetermined wavelength.
An area sensor, wherein each photoelectric conversion region corresponding to red light, green light, and blue light is provided with a plurality of regions having different filter transmittances by dividing each photoelectric conversion region in the predetermined direction.   An image reading apparatus using the area sensor according to claim 1.

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